Subscribe to RSS
![](/products/assets/desktop/img/oa-logo.png)
DOI: 10.1055/s-0042-102200
A New Dinor-cis-Labdane Diterpene and Flavonoids with Antimycobacterium Activity from Colebrookea oppositifolia
Correspondence
Publication History
received 16 October 2015
revised 15 December 2015
accepted 15 January 2016
Publication Date:
14 March 2016 (online)
Abstract
The new 14,15-dinor-cis-labdane diterpene, named (+)-14,15-dinor-9α-hydroxy-cis-labd-11(E)-en-13-one (1), was isolated from the acetone extract of the aerial parts of Colebrookea oppositifolia, along with the known compounds alnustin (2), mosloflavone (3), flindulatin (4), 5,6,7-trimethoxy baicalein (5), tanetin (6), scutellarein 4′-methyl ether (7), apigenin (8), caffeic acid (9), anisofolin A (10), apigetrin (11), and forsythoside A (12). Structures of the new and known compounds were established by detailed analysis of 1D and 2D nuclear magnetic resonance studies. The isolated compounds 1–12 were evaluated for their antimycobacterium activity against Mycobacterium tuberculosis H37Ra and Mycobacterium bovis in both dormant and active phases. Compounds 1, 7, and 8 exhibited inhibitory activity against M. tuberculosis with IC50 values in the range of 8.1–55.0 µM (MIC 14.4–119.7 µM) in the active phase and 7.4–43.5 µM (MIC 11.5–123.3 µM) in the dormant phase. Similarly 1, 7, and 8 exhibited inhibitory activity against M. bovis with IC50 values in the range of 4.1–98.5 µM (MIC 13.7–161.0 µM) in the active phase and 4.1–111.1 µM (MIC 13.0–166.4 µM) in the dormant phase.
#
Key words
Colebrookea oppositifolia - Lamiaceae - 14,15-dinor-cis-labdane diterpene - antimycobacterium - flavonoidsColebrookea (Lamiaceae) is a monotypic genus represented by Colebrookea oppositifolia Sm. (syn. = Colebrookea ternifolia Roxb.), commonly known as Panrasa, and is distributed in hilly parts of India and China [1], [2]. The roots of this shrub are used for epilepsy and the leaves are applied for wound healing and bruises [1], [2], [3]. It is used for the treatment of fractures, traumatic injuries, and rheumatoid arthritis in China [2]. Some other traditional uses are: the decoction of its roots is given as an abortifacient; the juice of the leaves is used to stop bleeding and as an eye and ear drop; and the paste of the leaves is applied to toothaches and mouth and tongue sores [4]. Different extracts of this shrub are reported to exhibit antibacterial [5], [6], [7], antimycobacterial [8], antioxidant [7], and antifertility [9] activities. Acteoside, a constituent from the aerial parts, exhibited an in vitro potent synergistic fungicidal effect in combination with amphotericin B [10]. Different parts of this plant have been studied phytochemically to isolate flavonoids [2], [11], [12], [13], [14], acteoside [10], sterols [15], and fatty compounds [11], [15].
Despite the availability of treatment, tuberculosis (TB) continues to be a deadly disease [16], [17], [18]. We are continuously involved in the process of the isolation of novel phytochemicals with promising anti-TB activity [19], [20], [21]. During our program for the isolation of anti-TB compounds from plants found in Western Ghats of Maharashtra, India, a phytochemical analysis of the acetone extract of the aerial parts of C. oppositifolia was performed. Herein we report the isolation and structure elucidation of compounds 1–12 ([Fig. 1]) and their evaluation for antimycobacterium activity against two microbial strains, Mycobacterium tuberculosis H37Ra and Mycobacterium bovis in both active and dormant phases.
![](https://www.thieme-connect.de/media/10.1055-s-00027015/201601/thumbnails/10-1055-s-0042-102200-ib0049pmle01.jpg)
![Zoom Image](/products/assets/desktop/css/img/icon-figure-zoom.png)
Compound 1 was obtained as yellow gum. Analysis of the 13 C NMR and DEPT-135 spectra revealed 18 resonances along with a pseudomolecular peak [M + Na]+ at m/z 301.2135 in the high-resolution electrospray ionization mass spectrometry (HRESIMS; Fig. 1 S, Supporting Information) and allowed for the determination of the molecular formula as C18H30O2, corresponding to four indices of the hydrogen deficiency. The 1 H NMR data ([Table 1]) showed the presence of four tertiary methyl singlets at δ H 0.86, 0.90, 1.06, and 2.27, and one secondary methyl at δ H 0.72 with coupling constant 6.8 Hz. Two methine protons at δ H 6.35 and 6.80 with coupling constant 15.9 Hz suggested the presence of a trans double bond. 13 C NMR data ([Table 1]) showed the presence of a carbonyl carbon at δ C 197.8 and two methine carbons at δ C 130.1 and 151.4 accounted for two indices of hydrogen deficiencies, suggesting that 1 was a bicyclic diterpenoid. The NMR data of 1 was similar to previously reported dinor-labdane diterpene, 8-hydroxy-14,15-dinor-11-labden-13-one [22], [23], except that a tertiary carbon at δ C 73.5 at position C-8 was replaced by a methine carbon at δ C 34.0, and a methine carbon at δ C 67.0 at position C-9 was replaced by the oxygenated tertiary carbon at δ C 79.6 in compound 1. These observations established the 14,15-dinor diterpene skeleton for 1. The structure was confirmed by 2D NMR studies as follows: The methyl protons at δ H 0.86 and 0.90 showed the heteronuclear multiple bond correlation (HMBC; Fig. 6 S, Supporting Information) with a methylene carbon at δ C 41.6 and a quaternary carbon at δ C 33.4. A methine proton at δ H 1.50 showed the HMBC correlation with a methylene carbon at δ C 30.6 and with a methyl carbon at δ C 17.2. Methyl protons at δ H 0.72 and 1.06 and a methine proton at δ H 6.35 showed the HMBC correlation with an oxygenated tertiary carbon at δ C 79.6. This suggested the placement of an oxygenated tertiary carbon at position C-9 and a methyl (δ H 0.72) at position C-8 unequivocally. Other HMBC correlations from protons at δ H 6.35 and 6.80 with the ketonic carbonyl carbon at δ C 197.8 and a proton at δ H 6.35 with a methyl carbon at δ C 27.9 were also observed ([Fig. 2]). The correlation spectroscopy (COSY; Fig. 7 S, Supporting Information) correlations were observed between δ H 1.38 and 1.43, δ H 1.43 and 1.17, δ H 1.50 and 1.31, δ H 1.31 and 1.52, δ H 1.52 and 2.04, and δ H 2.04 and 0.72, and suggested a H2-1-H2-2-H2-3 and H1-5-H2-6-H2-7-H1-8-H3-17 linkage, which confirmed the presence of a decalin ring skeleton in 1 ([Fig. 2]).
![](https://www.thieme-connect.de/media/10.1055-s-00027015/201601/thumbnails/10-1055-s-0042-102200-ib0049pmle02.jpg)
![Zoom Image](/products/assets/desktop/css/img/icon-figure-zoom.png)
Position |
δ H |
δ C |
HMBC |
---|---|---|---|
1a 1b |
1.38 (m) 1.59 (m) |
21.4 |
– |
2a 2b |
1.43 (m) 1.52 (m) |
18.4 |
– |
3a 3b |
1.17 (m) 1.36 (m) |
41.6 |
C-18, C-19 |
4 |
– |
33.4 |
– |
5 |
1.50 (m) |
45.4 |
C-6, C-20 |
6a 6b |
1.31 (m) 1.65 (m) |
30.6 |
C-8 |
7a 7b |
1.12 (m) 1.52 (m) |
32.8 |
C-20 |
8 |
2.04 (m) |
34.0 |
C-6 |
9 |
– |
79.6 |
– |
10 |
– |
42.4 |
– |
11 |
6.80 (d, J = 15.9 Hz) |
151.4 |
C-13 |
12 |
6.35 (d, J = 15.9 Hz) |
130.1 |
C-9, C-13, C-16 |
13 |
– |
197.8 |
– |
16 |
2.27 |
27.9 |
– |
17 |
0.72 (d, J = 6.8 Hz) |
16.2 |
C-9 |
18 |
0.90 (s) |
33.7 |
C-3, C-4 |
19 |
0.86 (s) |
22.0 |
C-3, C-4 |
20 |
1.06 (s) |
17.2 |
C-5, C-7, C-9 |
Comparison of NMR values of 1 with those reported for 8-hydroxy-14,15-dinor-11-labden-13-one [22], [23] revealed a deviation in the chemical shift at the carbon 5, i.e., upfield shift by 10 ppm at C-5 in 1. This upfield shift of C-5 (~ 10 ppm) can be explained by the cis-fused A/B ring junction [24], [25]. The fused rings assume a nonsteroidal conformation (cis A/B ring junction), as revealed by the strong nuclear overhauser effect spectroscopy (NOESY; Fig. 8 S, Supporting Information) correlation observed between H3-20 (δ H 1.06) and H-5 (δ H 1.50) ([Fig. 2]). Other observed NOESY correlations were between δ H 1.06 and 6.80 and between δ H 1.06 and 2.04, and indicated that the presence of the side chain at position C-9 was β orientated and a methyl at position C-8 was α orientated. Thus, based on a combination of detailed analysis of the 2D NMR data and comparison of observed and literature NMR data with the reported compound [22], [23], 1 was identified as a new natural product, (+)-14,15-dinor-9α-hydroxy-cis-labd-11(E)-en-13-one, and belongs to the rare class of 14,15-dinor-diterpenes with a cis A/B ring junction.
Compounds 2–12 ([Fig. 1]) were identified by comparison with observed and literature NMR data, and supported by liquid chromatography electrospray ionization mass spectrometry (LCESIMS) data. Compounds 2–8 were identified as flavonoids alnustin (2) [26], mosloflavone (3) [27], flindulatin (4) [28], 5,6,7-trimethoxy baicalein (5) [29], tanetin (6) [30], scutellarein 4′-methyl ether (7) [31], and apigenin (8) [32]. Compound 9 was identified as a caffeic acid [33]. Compounds 10 and 11 were identified as flavonoid glycosides anisofolin A [34] and apigetrin [35], respectively. Compound 12 was identified as forsythoside A [36]. Compounds 2–4 and 6–12 are reported for the first time from the genus Colebrookea, except compound 5 was already reported from C. oppositifolia [12]. Anisofolin A (10), which was previously reported from Leucas mollissima Wall. ex Benth. (Lamiaceae) by Chinchansure and coworkers, with its antimycobacterium activity, is also reported in this study [21].
Material and Methods
General experimental procedures, chemical, and biochemicals: Melting points were measured on Buchi B-540 instrument. Optical rotations were measured with a JASCO P-1020 polarimeter. UV spectra were measured with a SpectraMax plus 384 Microplate Reader. The IR spectrum was measured with a Bruker ALPHA FT-IR Spectrometer. 1 H and 13 C NMR spectroscopic data were recorded on a Bruker Avance Ultra Shield NMR instrument (1 H: 500 MHz, 13 C: 125 MHz). LCESIMS data were recorded with an API-QSTAR-PULSAR spectrometer. HRESIMS data was recorded with a Thermo-scientific Q-Exactive spectrometer. The silica gel (100–200 and 230–400 mesh) was purchased from Thomas Baker Pvt. Ltd., Mumbai, India. Preparative TLC was carried out using TLC plates supplied by Merck Ltd. MTT and rifampicin were purchased from Sigma-Aldrich, USA. M. tuberculosis H37Ra (ATCC No. 25 177) and M. bovis (ATCC 35 734) were obtained from AstraZeneca, India.
Plant material: C. oppositifolia aerial parts were collected from Mulshi, District Pune, India on January 12, 2013 and were identified by Dr. Swati Joshi, CSIR-NCL, Pune. A herbarium (Voucher No. HVT-1) was deposited in the Botanical Survey of India, Western Circle, Pune. The plant was cleaned, shade dried, cut, and pulverized.
Extraction and isolation: Pulverized aerial parts, 2.9 kg, were extracted with acetone, 6 L × 3 × 14 h, at room temperature. The acetone solubles were filtered and concentrated under reduced pressure to yield a greenish extract (165.7 g, 5.7 % based on dry plant weight), 100 g of which was separated by column chromatography (CC) using a gradient of acetone in petroleum ether from 10 to 100 % as an eluent to collect 150 fractions. Fractions showing a similar TLC pattern were combined to afford 16 fractions (COA1–COA16). The isolation of compounds 1–12 is provided in Supporting Information.
(+)-14,15-Dinor-9α-hydroxy-cis-labd-11(E)-en-13-one (1): yellow gum; [α]D 26 + 14.8 (c 0.55, CHCl3); UV (MeOH) λ max: 240 nm; IR (Nujol) ν max: 3508, 2924, 1736, 1710, 1673, 1456, 1270, 986 cm− 1; 1 H NMR (CDCl3, 500 MHz) and 13 C NMR (CDCl3, 125 MHz), see [Table 1]; HRESIMS m/z: 301.2135 [M + Na]+ (calculated for C18H30O2, 278.2246).
Antimycobacterial assay: M. tuberculosis H37Ra (ATCC No. 25 177) and M. bovis (ATCC 35 734) strains were tested for their susceptibility to compounds 1–12 in active and dormant phases by using the XRMA protocol. All the experiments were performed in triplicate, and IC50 and MIC values were calculated from their dose-response curves. The MIC was defined as the lowest concentration of the anti-tubercular agents that prevented visible growth with respect to the growth control [37], [38], [39]. Rifampicin was used as a positive control.
Compounds 1, 7, and 8 exhibited inhibitory activity against M. tuberculosis with IC50 values in the range of 8.1–55.0 µM (MIC 14.4–119.7 µM) in the active phase and 7.4–43.5 µM (MIC 11.5–123.3 µM) in the dormant phase ([Table 2]). Similarly 1, 7, and 8 exhibited inhibitory activity against M. bovis with IC50 values in the range of 4.1–98.5 µM (MIC 13.7–161.0 µM) in the active phase and 4.1–111.1 µM (MIC 13.0–166.4 µM) in the dormant phase ([Table 2]).
Compound |
Mycobacterium tuberculosis H37Ra |
Mycobacterium bovis |
||
---|---|---|---|---|
Active |
Dormant |
Active |
Dormant |
|
IC50* (MIC*) |
IC50* (MIC*) |
IC50* (MIC*) |
IC50* (MIC*) |
|
* µM = micro molar |
||||
1 |
55.0 ± 0.3 (119.7 ± 0.4) |
43.5 ± 0.2 (123.3 ± 0.1) |
98.5 ± 0.2 (161.0 ± 0.1) |
111.1 ± 0.4 (166.4 ± 0.3) |
7 |
23.7 ± 0.2 (80.3 ± 0.3) |
32.6 ± 0.3 (77.6 ± 0.4) |
16.6 ± 0.2 (46.3 ± 0.4) |
13.0 ± 0.4 (27.6 ± 0.1) |
8 |
8.1 ± 0.1 (14.4 ± 0.2) |
7.4 ± 0.2 (11.5 ± 0.4) |
4.1 ± 0.1 (13.7 ± 0.1) |
4.1 ± 0.3 (13.0 ± 0.3) |
Rifampicin |
0.0021 ± 0.0004 (0.019 ± 0.003) |
0.021 ± 0.005 (0.031 ± 0.003) |
0.0065 ± 0.0003 (0.034 ± 0.004) |
0.018 ± 0.001 (0.037 ± 0.002) |
Supporting information
HRESIMS and 1D and 2D NMR data of compound 1, dose dependence curves for compound 1, the isolation of compounds 1–12, and NMR and other characterization data for compounds 2–12 are available as Supporting Information.
#
#
Acknowledgements
We wish to thank Dr. Shanthakumari, Center for Material Characterization, National Chemical Laboratory, Pune, for HRESIMS analysis. We are grateful to the Council of Scientific and Industrial Research (CSIR), New Delhi, India, for a research fellowship.
#
#
Conflict of Interest
The authors declare no conflict of interest.
-
References
- 1 Bhatnagar SS, Chopra RN, Prashad B, Ghosh JC, Saha MN, Lala SR, Santapau H, Sastri BN. The Wealth of India: a dictionary of Indian raw materials & industrial products, Vol. 2. New Delhi: CSIR; 1950: 308
- 2 Yang F, Li XC, Wang HQ, Yang CR. Flavonoid glycosides from Colebrookea oppositifolia . Phytochemistry 1996; 42: 867-869
- 3 Chopra RN, Nayar SL, Chopra IC. Glossary of Indian medicinal plants. New Delhi: Council of Scientific and Industrial Research;; 1956. 1. 74
- 4 Thakur S, Sidhu MC. Phytochemical screening of some traditional medicinal plants. Res J Pharm Biol Chem Sci 2014; 5: 1088-1097
- 5 Ahmed T, Kanwal R, Hassan M, Ayub N. Assessment of antibacterial activity of Colebrookia oppositifolia against waterborne pathogens isolated from drinking water of the Pothwar region in Pakistan. Hum Ecol Risk Assess 2009; 15: 401-415
- 6 Shirsat R, Suradhar S, Koche D. Preliminary phytochemistry and antimicrobial activity of Salvia plebeia R. Br. and Colebrookea oppositifolia Smith. Int J Pure Appl Sci Technol 2014; 20: 21-24
- 7 Subba B, Basnet P. Antimicrobial and antioxidant activity of some indigenous plants of Nepal. J Pharmacogn Phytochem 2014; 3: 62-67
- 8 Gupta VK, Shukla C, Bisht GRS, Saikia D, Kumar S, Thakur RL. Detection of anti-tuberculosis activity in some folklore plants by radiometric BACTEC assay. Lett Appl Microbiol 2011; 52: 33-40
- 9 Gupta RS, Yadav RK, Dixit VP, Dobhal MP. Antifertility studies of Colebrookia oppositifolia leaf extract in male rats with special reference to testicular cell population dynamics. Fitoterapia 2001; 72: 236-245
- 10 Ali I, Sharma P, Suri KA, Satti NK, Dutt P, Afrin F, Khan IA. In vitro antifungal activities of amphotericin B in combination with acteoside, a phenylethanoid glycoside from Colebrookea oppositifolia . J Med Microbiol 2011; 60: 1326-1336
- 11 Ansari S, Dobhal MP, Tyagi RP, Joshi BC, Barar FSK. Chemical investigation and pharmacological screening of the roots of Colebrookia oppositifolia Smith. Pharmazie 1982; 37: 70
- 12 Patwardhan SA, Gupta AS. Two New flavones from Colebrookea oppositifolia . Indian J Chem 1981; 20?B: 627
- 13 Mukherjee PK, Mukherjee K, Hermans-Lokkerbol ACJ, Verpoorte R, Suresh B. Flavonoid content of Eupatorium glandulosum and Coolebroke oppositifolia . J Nat Remedies 2001; 1: 21-24
- 14 Reddy RVN, Reddy BAK, Gunasekaran D. A new acylated flavone glycoside from Colebrookea oppositifolia . J Asian Nat Prod Res 2009; 11: 183-186
- 15 Verma SK, Parrek D, Singhal R, Chauhan AK, Parashar P, Dobal MP. Ferulic acid ester from Colebrookea oppositifolia . Indian J Chem 2012; 51?B: 1502-1503
- 16 Dashti Y, Grkovic T, Quinn RJ. Predicting natural product value, an exploration of anti-TB drug space. Nat Prod Rep 2014; 31: 990-998
- 17 World Health Organization. Global tuberculosis report 2014. Geneva: WHO Press; 2014: 1-171
- 18 World Health Organization. Drug-resistant TB surveillance & response. Supplement – global tuberculosis report 2014. Geneva: WHO Press; 2014: 1-32
- 19 Kulkarni RR, Shurpali K, Puranik VG, Sarkar D, Joshi SP. Antimycobacterial labdane diterpenes from Leucas stelligera . J Nat Prod 2013; 76: 1836-1841
- 20 Kulkarni RR, Joshi SP. New 2, 2-diphenylpropane and ethoxylated aromatic monoterpenes from Lavandula gibsoni (Lamiaceae). Nat Prod Res 2013; 27: 1323-1329
- 21 Chinchansure AA, Arkile M, Shukla A, Dhanasekaran S, Sarkar D, Joshi SP. Leucas mollissima, a source of bioactive compounds with antimalarial and antimycobacterium activities. Planta Med Lett 2015; 2: e35-e38
- 22 Yang XW, Li SM, Feng L, Shen YH, Tian JM, Liu XH, Zeng HW, Zhang C, Zhang WD. Abiesanordines A–N: fourteen new norditerpenes from Abies georgei . Tetrahedron 2008; 64: 4354-4362
- 23 Kinouchi Y, Ohtsu H, Tokuda H, Nishino H, Matsunaga S, Tanaka R. Potential antitumor-promoting diterpenoids from the stem bark of Picea glehni . J Nat Prod 2000; 63: 817-820
- 24 Kulkarni RR, Shurpali K, Puranik VG, Sarkar D, Joshi SP. Antimycobacterial labdane diterpenes from Leucas stelligera . J Nat Prod 2013; 76: 1836-1841
- 25 Torrenegra R, Pedrozo J, Robles J, Waibel R, Achenbach H. Diterpenes from Gnaphalium pellitum and Gnaphalium graveolens . Phytochemistry 1992; 31: 2415-2418
- 26 Asakawa Y. Chemical constituents of Alnus sieboldiana (Betulaceae) II. The isolation and structure of flavonoids and stilbenes. Bull Chem Soc Jpn 1971; 44: 2761-2766
- 27 Panichpol K, Waterman PG. Novel flavonoids from the stem of Popowia cauliflora . Phytochemistry 1978; 17: 1363-1367
- 28 Su BN, Park EJ, Vigo JS, Graham JG, Cabieses F, Fong HHS, Pezzuto JM, Kinghorn AD. Activity-guided isolation of the chemical constituents of Muntingia calabura using a quinone reductase induction assay. Phytochemistry 2003; 63: 335-341
- 29 Iinuma M, Matsuura S, Kusuda K. 13 C-Nuclear magnetic resonance (NMR) spectral studies on polysubstituted flavonoids. I. 13 C-NMR spectra of flavones. Chem Pharm Bull 1980; 28: 708-716
- 30 Williams CA, Hoult JRS, Harborne JB, Greenham J, Eagles J. Biologically active lipophilic flavonol from Tanacetum parthenium . Phytochemistry 1995; 38: 267-270
- 31 Sabina H, Aliya R. Bioactive assessment of selected marine red algae against Leishmania major and chemical constituents of Osmundea pinnatifida . Pak J Bot 2011; 43: 3053-3056
- 32 Chen GY, Dai CY, Wang TS, Jiang CW, Han CR, Song XP. A new flavonol from the stem-bark of Premna fulva . Arkivoc 2010; 179-185
- 33 Wei Y, Gao Y, Zhang K, Ito Y. Isolation of caffeic acid from Eupatorium adenophorum Spreng by high-speed counter current chromatography and synthesis of caffeic acid-intercalated layered double hydroxide. J Liq Chromatogr Relat Technol 2010; 33: 837-845
- 34 Rao LJM, Kumari GNK, Rao NSP. Anisofolin-A, a new acylated flavone glucoside from Anisomeles ovata R. Br. Heterocycles 1982; 19: 1655-1661
- 35 Švehlíková V, Bennett RN, Mellon FA, Needs PW, Piacente S, Kroon PA, Bao Y. Isolation, identification and stability of acylated derivatives of apigenin 7-O-glucoside from chamomile (Chamomilla recutita [L.] Rauschert). Phytochemistry 2004; 65: 2323-2332
- 36 Yang M, Xu X, Xie C, Huang J, Xie Z, Yang D. Isolation and purification of forsythoside A and suspensaside A from Forsythia suspensa by high-speed counter-current chromatography. J Liq Chromatogr Relat Technol 2013; 36: 2895-2904
- 37 Dzoyem JP, Guru SK, Pieme CA, Kuete V, Sharma A, Khan IA, Saxena AK, Vishwakarma RA. Cytotoxic and antimicrobial activity of selected Cameroonian edible plants. BMC Complement Altern Med 2013; 13: 78-84
- 38 Singh U, Akhtar S, Mishra A, Sarkar D. A novel screening method based on menadione mediated rapid reduction of tetrazolium salt for testing of anti-mycobacterial agents. J Microbiol Methods 2011; 84: 202-207
- 39 Khan A, Sarkar D. A simple whole cell based high throughput screening protocol using Mycobacterium bovis BCG for inhibitors against dormant and active tubercle bacilli. J Microbiol Methods 2008; 73: 62-68
Correspondence
-
References
- 1 Bhatnagar SS, Chopra RN, Prashad B, Ghosh JC, Saha MN, Lala SR, Santapau H, Sastri BN. The Wealth of India: a dictionary of Indian raw materials & industrial products, Vol. 2. New Delhi: CSIR; 1950: 308
- 2 Yang F, Li XC, Wang HQ, Yang CR. Flavonoid glycosides from Colebrookea oppositifolia . Phytochemistry 1996; 42: 867-869
- 3 Chopra RN, Nayar SL, Chopra IC. Glossary of Indian medicinal plants. New Delhi: Council of Scientific and Industrial Research;; 1956. 1. 74
- 4 Thakur S, Sidhu MC. Phytochemical screening of some traditional medicinal plants. Res J Pharm Biol Chem Sci 2014; 5: 1088-1097
- 5 Ahmed T, Kanwal R, Hassan M, Ayub N. Assessment of antibacterial activity of Colebrookia oppositifolia against waterborne pathogens isolated from drinking water of the Pothwar region in Pakistan. Hum Ecol Risk Assess 2009; 15: 401-415
- 6 Shirsat R, Suradhar S, Koche D. Preliminary phytochemistry and antimicrobial activity of Salvia plebeia R. Br. and Colebrookea oppositifolia Smith. Int J Pure Appl Sci Technol 2014; 20: 21-24
- 7 Subba B, Basnet P. Antimicrobial and antioxidant activity of some indigenous plants of Nepal. J Pharmacogn Phytochem 2014; 3: 62-67
- 8 Gupta VK, Shukla C, Bisht GRS, Saikia D, Kumar S, Thakur RL. Detection of anti-tuberculosis activity in some folklore plants by radiometric BACTEC assay. Lett Appl Microbiol 2011; 52: 33-40
- 9 Gupta RS, Yadav RK, Dixit VP, Dobhal MP. Antifertility studies of Colebrookia oppositifolia leaf extract in male rats with special reference to testicular cell population dynamics. Fitoterapia 2001; 72: 236-245
- 10 Ali I, Sharma P, Suri KA, Satti NK, Dutt P, Afrin F, Khan IA. In vitro antifungal activities of amphotericin B in combination with acteoside, a phenylethanoid glycoside from Colebrookea oppositifolia . J Med Microbiol 2011; 60: 1326-1336
- 11 Ansari S, Dobhal MP, Tyagi RP, Joshi BC, Barar FSK. Chemical investigation and pharmacological screening of the roots of Colebrookia oppositifolia Smith. Pharmazie 1982; 37: 70
- 12 Patwardhan SA, Gupta AS. Two New flavones from Colebrookea oppositifolia . Indian J Chem 1981; 20?B: 627
- 13 Mukherjee PK, Mukherjee K, Hermans-Lokkerbol ACJ, Verpoorte R, Suresh B. Flavonoid content of Eupatorium glandulosum and Coolebroke oppositifolia . J Nat Remedies 2001; 1: 21-24
- 14 Reddy RVN, Reddy BAK, Gunasekaran D. A new acylated flavone glycoside from Colebrookea oppositifolia . J Asian Nat Prod Res 2009; 11: 183-186
- 15 Verma SK, Parrek D, Singhal R, Chauhan AK, Parashar P, Dobal MP. Ferulic acid ester from Colebrookea oppositifolia . Indian J Chem 2012; 51?B: 1502-1503
- 16 Dashti Y, Grkovic T, Quinn RJ. Predicting natural product value, an exploration of anti-TB drug space. Nat Prod Rep 2014; 31: 990-998
- 17 World Health Organization. Global tuberculosis report 2014. Geneva: WHO Press; 2014: 1-171
- 18 World Health Organization. Drug-resistant TB surveillance & response. Supplement – global tuberculosis report 2014. Geneva: WHO Press; 2014: 1-32
- 19 Kulkarni RR, Shurpali K, Puranik VG, Sarkar D, Joshi SP. Antimycobacterial labdane diterpenes from Leucas stelligera . J Nat Prod 2013; 76: 1836-1841
- 20 Kulkarni RR, Joshi SP. New 2, 2-diphenylpropane and ethoxylated aromatic monoterpenes from Lavandula gibsoni (Lamiaceae). Nat Prod Res 2013; 27: 1323-1329
- 21 Chinchansure AA, Arkile M, Shukla A, Dhanasekaran S, Sarkar D, Joshi SP. Leucas mollissima, a source of bioactive compounds with antimalarial and antimycobacterium activities. Planta Med Lett 2015; 2: e35-e38
- 22 Yang XW, Li SM, Feng L, Shen YH, Tian JM, Liu XH, Zeng HW, Zhang C, Zhang WD. Abiesanordines A–N: fourteen new norditerpenes from Abies georgei . Tetrahedron 2008; 64: 4354-4362
- 23 Kinouchi Y, Ohtsu H, Tokuda H, Nishino H, Matsunaga S, Tanaka R. Potential antitumor-promoting diterpenoids from the stem bark of Picea glehni . J Nat Prod 2000; 63: 817-820
- 24 Kulkarni RR, Shurpali K, Puranik VG, Sarkar D, Joshi SP. Antimycobacterial labdane diterpenes from Leucas stelligera . J Nat Prod 2013; 76: 1836-1841
- 25 Torrenegra R, Pedrozo J, Robles J, Waibel R, Achenbach H. Diterpenes from Gnaphalium pellitum and Gnaphalium graveolens . Phytochemistry 1992; 31: 2415-2418
- 26 Asakawa Y. Chemical constituents of Alnus sieboldiana (Betulaceae) II. The isolation and structure of flavonoids and stilbenes. Bull Chem Soc Jpn 1971; 44: 2761-2766
- 27 Panichpol K, Waterman PG. Novel flavonoids from the stem of Popowia cauliflora . Phytochemistry 1978; 17: 1363-1367
- 28 Su BN, Park EJ, Vigo JS, Graham JG, Cabieses F, Fong HHS, Pezzuto JM, Kinghorn AD. Activity-guided isolation of the chemical constituents of Muntingia calabura using a quinone reductase induction assay. Phytochemistry 2003; 63: 335-341
- 29 Iinuma M, Matsuura S, Kusuda K. 13 C-Nuclear magnetic resonance (NMR) spectral studies on polysubstituted flavonoids. I. 13 C-NMR spectra of flavones. Chem Pharm Bull 1980; 28: 708-716
- 30 Williams CA, Hoult JRS, Harborne JB, Greenham J, Eagles J. Biologically active lipophilic flavonol from Tanacetum parthenium . Phytochemistry 1995; 38: 267-270
- 31 Sabina H, Aliya R. Bioactive assessment of selected marine red algae against Leishmania major and chemical constituents of Osmundea pinnatifida . Pak J Bot 2011; 43: 3053-3056
- 32 Chen GY, Dai CY, Wang TS, Jiang CW, Han CR, Song XP. A new flavonol from the stem-bark of Premna fulva . Arkivoc 2010; 179-185
- 33 Wei Y, Gao Y, Zhang K, Ito Y. Isolation of caffeic acid from Eupatorium adenophorum Spreng by high-speed counter current chromatography and synthesis of caffeic acid-intercalated layered double hydroxide. J Liq Chromatogr Relat Technol 2010; 33: 837-845
- 34 Rao LJM, Kumari GNK, Rao NSP. Anisofolin-A, a new acylated flavone glucoside from Anisomeles ovata R. Br. Heterocycles 1982; 19: 1655-1661
- 35 Švehlíková V, Bennett RN, Mellon FA, Needs PW, Piacente S, Kroon PA, Bao Y. Isolation, identification and stability of acylated derivatives of apigenin 7-O-glucoside from chamomile (Chamomilla recutita [L.] Rauschert). Phytochemistry 2004; 65: 2323-2332
- 36 Yang M, Xu X, Xie C, Huang J, Xie Z, Yang D. Isolation and purification of forsythoside A and suspensaside A from Forsythia suspensa by high-speed counter-current chromatography. J Liq Chromatogr Relat Technol 2013; 36: 2895-2904
- 37 Dzoyem JP, Guru SK, Pieme CA, Kuete V, Sharma A, Khan IA, Saxena AK, Vishwakarma RA. Cytotoxic and antimicrobial activity of selected Cameroonian edible plants. BMC Complement Altern Med 2013; 13: 78-84
- 38 Singh U, Akhtar S, Mishra A, Sarkar D. A novel screening method based on menadione mediated rapid reduction of tetrazolium salt for testing of anti-mycobacterial agents. J Microbiol Methods 2011; 84: 202-207
- 39 Khan A, Sarkar D. A simple whole cell based high throughput screening protocol using Mycobacterium bovis BCG for inhibitors against dormant and active tubercle bacilli. J Microbiol Methods 2008; 73: 62-68
![](https://www.thieme-connect.de/media/10.1055-s-00027015/201601/thumbnails/10-1055-s-0042-102200-ib0049pmle01.jpg)
![Zoom Image](/products/assets/desktop/css/img/icon-figure-zoom.png)
![](https://www.thieme-connect.de/media/10.1055-s-00027015/201601/thumbnails/10-1055-s-0042-102200-ib0049pmle02.jpg)
![Zoom Image](/products/assets/desktop/css/img/icon-figure-zoom.png)